The present invention relates to a piezoelectric element for power generation and a power generation device using the same, and more specifically, to a piezoelectric element for power generation and a power generation device using the same, which can maximize an electromotive force generated by the piezoelectric element by converting an external force (a natural force, a load force of a person/vehicle or the like) transferred from outside into an instantaneous impact force and transferring the impact force to the piezoelectric element.
Generally, a piezoelectric element is a device having a property of generating an electromotive force using a potential difference generated by electrical polarization when a mechanical pressure is applied from outside and, contrarily, generating deformation or stress when a voltage is applied, and although the piezoelectric element is used in an oscillator, a speaker or the like in the prior art, a lot of attempts have been made recently to use the piezoelectric element to generate power as a kind of new and renewable energy.
A power generation device using a piezoelectric element according to a conventional technique chiefly uses a method of generating electricity by directly pressing or deforming the piezoelectric element using an external force such as a load of a person or a vehicle, and details thereof are specifically disclosed in the [Document 1] and the like described below.
However, the piezoelectric element for power generation according to the conventional technique has a problem in that since an external force is applied for a relatively long period of time as much as several tens or hundreds of milliseconds, a generated voltage is extremely low due to the characteristic of a piezoelectric material, in which magnitude of an electromotive force generated when an external force of the same magnitude is applied is inverse proportional to the time of applying the external force, and thus it is difficult to accomplish commercialization of the piezoelectric element with economic feasibility.
In order to solve such a problem of the conventional technique, a piezoelectric element for generating power using an elastic impact force of a very high frequency, which is generated when a metal thin film is elastically deformed by an external force, has been developed recently as shown in the [Document 2] applied by the inventors of the present invention
However, since even the piezoelectric element disclosed in the [Document 2] described below uses a method of fixing a piezoelectric ceramic on a curved deformation surface of a metal thin film which repeats elastic deformation and restoration by an external force, there is a problem in that the curved surface of the metal thin film is not tightly attached to the piezoelectric ceramic when the piezoelectric element is manufactured.
Furthermore, in the case of the piezoelectric element disclosed in the [Document 2] described below, since the curved surface on which the piezoelectric ceramic is fixed is configured to directly generate elastic deformation by an external force, a strong elastic impact force generated by deformation of the curved surface is directly transferred to the piezoelectric ceramic, and thus there is a problem in that the piezoelectric ceramic is damaged and does not maintain a function as a piezoelectric element.                [Document 1] Korean Patent Registration No. 988077 (Disclosed on Oct. 18, 2010)        [Document 2] Korean Patent Registration No. 1132934 (Disclosed on Mar. 27, 2012)        